Some types of databases are intended to maintain electronic data for extremely long periods of time. For example, health record databases may maintain health data for individuals on an indefinite basis, such as for the life of the individual or longer. Similarly, some financial record databases, due diligence databases, and other types of databases also are used to maintain records on an indefinite basis or for very long periods of time.
In these types of databases, it is desirable for the data to be maintained in a complete and accessible form despite changes that may occur over time in the types of computer programs and equipment that are used to provide the data, access the data or modify the data. For example, because these databases maintain data in an electronic format, the applications used to store and access the data can change as applications become obsolete or new technologies are created. In particular, a data type may be stored initially using a particular format or schema of data elements corresponding to a particular application. However, over time, the data of that data type might also be stored or formatted using other formats and schemas that contain new or different data elements, different ordering of data elements, or the like. When such changes occur, data that was originally stored in a first format by an application that is now obsolete may not be able to be accessed or read by any currently available applications, or data that is created by new applications may not be backward compatible with some existing applications. However, as mentioned above, certain types of data are expected to remain accessible, regardless of the length of time that has elapsed, and regardless the particular application or schema that was used to originally store the data.